From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752118AbaBYK1y (ORCPT ); Tue, 25 Feb 2014 05:27:54 -0500 Received: from www.linutronix.de ([62.245.132.108]:35838 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751044AbaBYK1v (ORCPT ); Tue, 25 Feb 2014 05:27:51 -0500 Date: Tue, 25 Feb 2014 11:27:52 +0100 (CET) From: Thomas Gleixner To: Russ Dill cc: Sebastian Capella , Russell King - ARM Linux , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linaro-kernel@lists.linaro.org, linux-arm-kernel@lists.infradead.org, Andrew Morton , Will Deacon , Robin Holt Subject: Re: [PATCH RFC v1 1/3] ARM: Add irq disabled version of soft_restart. In-Reply-To: <530C4CAE.5000202@ti.com> Message-ID: References: <1392774729-3235-1-git-send-email-sebastian.capella@linaro.org> <1392774729-3235-2-git-send-email-sebastian.capella@linaro.org> <20140222102616.GG21483@n2100.arm.linux.org.uk> <20140224231345.10580.62916@capellas-linux> <530C4CAE.5000202@ti.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 24 Feb 2014, Russ Dill wrote: > On 02/24/2014 03:13 PM, Sebastian Capella wrote: > > Quoting Russell King - ARM Linux (2014-02-22 02:26:17) > >> On Tue, Feb 18, 2014 at 05:52:07PM -0800, Sebastian Capella wrote: > >>> From: Russ Dill > >>> > >>> This adds the ability to run soft_restart with local_irq/fiq_disable > >>> already called. This is helpful for the hibernation code paths. > >> > >> I'd rather keep this simple. There's no problem with calling soft_restart > >> with interrupts already disabled. local_irq_disable()/local_fiq_disable() > >> there should be harmless. > > > > Hi Russell, > > > > I'm observing a data abort loop when I replace this call: > > > > In the local_irq_disable, it ends up calling trace_hardirqs_off > > (CONFIG_TRACE_IRQFLAGS_SUPPORT is enabled), which calls > > trace_hardirqs_off_caller which checks lockdep_recursion in the > > current task, but we've switched to a temporary stack with the > > call_with_stack, and get_current is returning NULL. This > > triggers a data abort, which calls trace_hardirqs_off > > again and so on. > > > > Do you have any suggestions here? > > > > Thanks, > > > > Sebastian > > > > So the alternative is to have a version of the call that calls a special > no trace version of local_irq_disable()/local_fiq_disable(). Which would > be preferable? Having a noirq version of soft_restart seems much simpler > to me. If you want escape the tracer and in that case you really want it being on a different stack, use raw_local_irq_* which are not traced. Thanks, tglx From mboxrd@z Thu Jan 1 00:00:00 1970 From: tglx@linutronix.de (Thomas Gleixner) Date: Tue, 25 Feb 2014 11:27:52 +0100 (CET) Subject: [PATCH RFC v1 1/3] ARM: Add irq disabled version of soft_restart. In-Reply-To: <530C4CAE.5000202@ti.com> References: <1392774729-3235-1-git-send-email-sebastian.capella@linaro.org> <1392774729-3235-2-git-send-email-sebastian.capella@linaro.org> <20140222102616.GG21483@n2100.arm.linux.org.uk> <20140224231345.10580.62916@capellas-linux> <530C4CAE.5000202@ti.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, 24 Feb 2014, Russ Dill wrote: > On 02/24/2014 03:13 PM, Sebastian Capella wrote: > > Quoting Russell King - ARM Linux (2014-02-22 02:26:17) > >> On Tue, Feb 18, 2014 at 05:52:07PM -0800, Sebastian Capella wrote: > >>> From: Russ Dill > >>> > >>> This adds the ability to run soft_restart with local_irq/fiq_disable > >>> already called. This is helpful for the hibernation code paths. > >> > >> I'd rather keep this simple. There's no problem with calling soft_restart > >> with interrupts already disabled. local_irq_disable()/local_fiq_disable() > >> there should be harmless. > > > > Hi Russell, > > > > I'm observing a data abort loop when I replace this call: > > > > In the local_irq_disable, it ends up calling trace_hardirqs_off > > (CONFIG_TRACE_IRQFLAGS_SUPPORT is enabled), which calls > > trace_hardirqs_off_caller which checks lockdep_recursion in the > > current task, but we've switched to a temporary stack with the > > call_with_stack, and get_current is returning NULL. This > > triggers a data abort, which calls trace_hardirqs_off > > again and so on. > > > > Do you have any suggestions here? > > > > Thanks, > > > > Sebastian > > > > So the alternative is to have a version of the call that calls a special > no trace version of local_irq_disable()/local_fiq_disable(). Which would > be preferable? Having a noirq version of soft_restart seems much simpler > to me. If you want escape the tracer and in that case you really want it being on a different stack, use raw_local_irq_* which are not traced. Thanks, tglx